The Yuthlugathap Swamps

From the front of the book:

THE YUTHLUGATHAP SWAMPS contains a large-scale hex map, introductory information, geographical notes, and detailed encounters keyed to the map. This module presents a complete setting for ADVANCED DUNGEONS & DRAGONS, intended for use by experienced Dungeon Masters. It can be used on its own, in conjunction with your own campaign world, or as the northwest quarter of a larger campaign area that includes BARRENS OF CARCOSA, JUNGLES OF THE K'NAANOTHOA, and THE MOUNTAINS OF DREAM.